Problem: Solve for $x$ : $2x + 3 = 9x + 4$
Explanation: Subtract $2x$ from both sides: $(2x + 3) - 2x = (9x + 4) - 2x$ $3 = 7x + 4$ Subtract $4$ from both sides: $3 - 4 = (7x + 4) - 4$ $-1 = 7x$ Divide both sides by $7$ $\dfrac{-1}{7} = \dfrac{7x}{7}$ Simplify. $-\dfrac{1}{7} = x$